Graduate Studies

 

First Advisor

Peisi Huang

Degree Name

Doctor of Philosophy (Ph.D.)

Committee Members

Kenneth Bloom, Bradley Shadwick, Adam Larios

Department

Physics and Astronomy

Date of this Version

5-2024

Document Type

Dissertation

Citation

A dissertation presented to the faculty of the Graduate College of the University of Nebraska in partial fulfillment of requirements for the degree of Doctor of Philosophy

Major: Physics and Astronomy

Under the supervision of Professor Peisi Huang

Lincoln, Nebraska, May 2024

Comments

Copyright 2024, Anthony James Hooper. Used by permission

Abstract

The large matter-antimatter asymmetry of the universe and whether the electroweak sector has always been broken are currently unanswered by the standard model (SM). One solution that addresses both these concerns is to impose a strong first order electroweak phase transition (SFOEWPT) and ensure electroweak baryogenesis occurs. Models that undergo a SFOEWPT in the early universe create bubbles of the true vacuum that expand until the universe reaches the vacuum expectation value measured today. If the phase transition is strong enough, then these bubbles may generate a detectable stochastic gravitational wave (GW).

However, the SM by itself can only perform a smooth cross over phase transition, thus we extended the SM with a real scalar singlet and required the above criteria. Although the model is simple, the mixed-mass eigenstates create a rich phenomenology from light to heavy singlet masses. We analyzed the parameter space for singlets masses up to 2 TeV, carefully imposing the necessary theoretical and experimental constraints for each regime and ensuring that a SFOEWPT occurred. We found that much of the parameter space can be probed by future collider and GW experiments.

Advisor: Peisi Huang

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